Thermostats that control heating and air conditioning units typically have a temperature control range of forty to sixty degrees. It is often desirable to restrict the temperature range within which the thermostat can be operated. Toward this end, thermostat range limit devices have been proposed.
Examples of such devices are found in U.S. Pat. No. 4,639,709 issued to Koets and U.S. Pat. Nos. 4,090,165 and 3,999,158 issued to Rae. These devices narrow the range within which the thermostat control lever can operate and thereby restrict the range within which the temperature setting swings. These devices are relatively simple and efficient. However, they do suffer from major drawbacks.
The thermostat must be constrUCted so that it receives the particular range limit device. Therefore, in order to make use of these range limit devices, the thermostat housing must be able to receive the device. Otherwise, the housing must be retrofitted with the receiving means.
Furthermore, each of the above devices requires a partial disassembly of the thermostat housing in order to reset the range. Additionally, the two devices proposed by Rae require the storage of several parts to be used for the various ranges desired. Such parts will tend to be lost over time rendering the device useless.
The above drawbacks associated with the current range limit devices, will discourage installation and use of the devices. If a thermostat's housing is unable to receive a temperature range limit device, a person will be loath to pay for a retrofit. If the device is installed, many people will disassemble the thermostat housing in order to utilize the device.
What is needed is a thermostat range limit device that does not require any particular receiving means within the thermostat housing. Such a device must be able to be installed on any thermostat without the need for any alteration to the thermostat. This device must be easy to use without the need to partially disassemble the housing. Ideally, this device should be inexpensive to manufacture.